Three piece welded plastic pallet

ABSTRACT

A plastic pallet constructed of a synthetic resin material includes a top deck having an upper surface and a lower surface and a middle deck having an upper plate portion and a lower plate portion connected by a plurality of columns extending there between and integrally molded as a single piece. A bottom deck has an upper surface and a lower surface. The lower surface of the top deck is welded to the top surface of the upper plate portion and the bottom surface of the lower plate portion of the middle deck is welded to the upper surface of the bottom deck. Reinforcement members may be provided between the top deck and the middle deck and between the middle deck and the bottom deck.

BACK GROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pallet made of synthetic resin and, more particularly, to a three piece welded plastic pallet for supporting loads that is adapted for use with a lifting device.

2. Description of the Related Art

Plastic pallets are becoming more commonly used in today's industries. Plastic pallets have many advantages over those made of wood or even metal. Plastic pallets are stronger and more durable than wooden pallets and are impervious to most chemicals, do not rot and do not absorb moisture. Plastic pallets are also lighter than wood or metal pallets. Moreover, plastic pallets are not subject to corrosion or rusting.

Many of the plastic pallets in use today are constructed of top and bottom horizontal decks connected together by a series of columns or posts and have entryways for the forks of a lifting device such as a fork lift. In order to be strong enough to support heavier loads, however, many of the present plastic pallets have a large package height in order to be sufficiently strong. Such pallets are heavier and use relatively large amounts of plastic material. Other plastic pallets with a lower package height may not provide sufficient strength for heavier loads.

Accordingly, a need still exists for a plastic pallet which is reasonably inexpensive, sturdy, lightweight and still possesses sufficient strength for heavier loads. The pallet also should have sufficient stiffness to receive the fork of a lifting device without reducing the strength of the pallet.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a plastic pallet made of a synthetic resin which is formed from three separate pieces which are welded together.

A further object of the invention is to provide plastic pallet which possesses sufficient strength to support heavy loads but which is still relatively lightweight and durable.

It is another object of the invention to provide a plastic pallet which has a smooth outside surface which is easy to clean and is particularly useful in connection with handling foods and beverages.

A still further object of the invention is to provide a plastic pallet made from a synthetic resin such as polyethylene or polypropylene which is impervious to most chemicals, does not rot, does not absorb moisture, does not rust and maintains a constant tare weight.

The present invention achieves the above and other objects by providing a three piece plastic pallet constructed of a synthetic resin material and having a top deck with an upper surface and a lower surface. A middle deck is provided having an upper plate portion and lower portion spaced from each other and connected by plurality of columns extending between a lower surface of the upper plate portion and a top surface of the lower plate portion, with the upper plate portion having a top surface attached by welding to the lower surface of the top deck. A bottom deck is provided having an upper surface and a lower surface with the upper surface of the bottom deck being attached by welding to a bottom surface of the lower plate portion of the middle deck. Reinforcement members may be provided between the top deck and the middle deck and/or between the middle deck and the bottom deck to provide further strength to the pallet. Entryways for prongs of a lifting device such as a forklift may be formed on all four sides of the pallet.

The lower surface of the top deck has a plurality of first rib members thereon which mate with and are attached to a plurality of second rib members on the top surface of the upper plate portion of the middle deck and the bottom surface of the lower plate portion of the middle deck has a plurality of third rib members thereon which mate with and are attached to a plurality of fourth rib members on the upper surface of the bottom deck.

These and other features and advantages of the present invention will become more apparent with reference to the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a three piece plastic pallet according to the present invention;

FIG. 2 is an exploded, right side, perspective view from the top of the plastic pallet illustrating the three separate pieces;

FIG. 3 is an exploded, left side perspective view from the top showing the three pieces of the plastic pallet;

FIG. 4 is an exploded perspective view from the bottom of the pallet; and

FIG. 5 is an exploded top perspective view of another embodiment of the present invention showing reinforcement bars between the top and middle decks and between the middle and bottom decks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrated in FIGS. 1-4 of the drawings is a pallet 10 according to the present invention which includes a top deck 12, a middle deck 14 and a bottom deck 16. A plurality of entryways 18 are provided on the sides of the pallet with each side being constructed with two entryways to receive the prongs of a lifting device such as a forklift. The top, middle and bottom decks are all made of a synthetic resin or plastic material such as polypropylene or polyethylene. The three decks preferably are molded using an injection molding process.

The top deck 12 has a smooth upper surface 22 as shown in FIGS. 1-3 and a lower surface 24 having a plurality of ribs 26 which cross each other to form a plurality of diamond shaped boxes as shown in FIG. 4. The top deck also is provided with a plurality of holes constituting hand holds 28 adjacent the sides thereof.

As shown in FIGS. 2, 3 and 4, middle deck 14 is constructed having an upper plate portion 30 and a lower plate portion 32 connected by a plurality of columns or posts 34. As best shown in FIG. 4, the columns 34 extend between the upper plate portion 30 and the lower plate portion 32 whereby the two plate portions are spaced from each other a sufficient amount to permit the entryways 18 to be constructed along each side of the middle deck. Preferably, the columns 34 are aligned in rows of three both lengthwise and widthwise of the middle deck. Each of the columns has a hollow interior 35 provided with reinforcing dividers 37.

The upper plate portion 30 of the middle deck has a top surface 36 and a lower surface 38. The top surface 36 of the upper plate portion is provided with a plurality of ribs 40 which cross each other to form diamond shaped boxes of the same configuration as the ribs 26 on the lower surface 24 of the top deck whereby the ribs 40 and 26 mate when the top deck is welded to the upper plate portion of the middle deck.

The lower plate portion 32 of the middle deck has a top surface 42 and a bottom surface 44 having a plurality of ribs 46 thereon which cross each other to form rectangular boxes. The lower plate portion 32 is provided with a plurality of rectangular cutout portions 48, which reduce the amount of material required and also reduce the weight of the pallet.

The bottom deck 16 has an upper surface 50 and a smooth lower surface 52. The upper surface 50 of the bottom deck is provided with a plurality of ribs 54 which cross each other to form a plurality of rectangular boxes having the same configuration and which mate with the ribs 46 on the bottom surface of the lower plate portion of the middle deck when the bottom deck is attached by welding to the middle deck.

The bottom deck 16 is provided with a plurality of rectangular holes 56 which match with the rectangular holes 48 of the middle deck. The holes 56 in the bottom deck reduce the amount of material required to form the deck and also lessen the overall weight of the pallet.

In manufacturing the pallet 10, the top deck 22 is formed by injection molding as one integral piece, the middle deck 14 is formed by injection molding as a second single integral piece and the bottom deck 16 is formed by injection molding as a third integral piece. To assemble the three pieces into the pallet of the present invention, the top deck is attached by a suitable welding process such as flat plate welding to the upper plate portion of the middle deck and the bottom deck is attached by a suitable welding process such as flat plate welding to the lower plate portion of the middle deck. Other suitable forms of plastic welding may be used such as sonic welding or infrared radiation welding. This construction results in a pallet of superior strength. The entire middle deck is formed as an integral piece and then the top and bottom decks are welded to the middle deck to form a solid structure. This construction results in an I-beam type effect since the columns extend between the top deck and the bottom deck. The I-beam type construction results in a pallet with superior strength.

Moreover, the pallet maintains a deck thickness close of that of wood while still providing superior strength. In addition, the upper surface of the top deck and the lower surface of the bottom deck are smooth which makes them easy to clean. This feature is especially important in connection with food and beverage products.

Since the entire pallet is made from a synthetic resin such as polyethylene or polypropylene, it is impervious to most chemicals, does not rot, does not absorb moisture, has a constant tare weight and does not rust or otherwise deteriorate.

In a second embodiment of the invention shown in FIG. 5, additional strength may be added to the pallet by the use of reinforcement bars. As shown in FIG. 5, reinforcement bars 60 may be added between the top deck and the upper plate portion of the middle deck and additional reinforcement bars 62 may be added between the lower deck and lower surface of the bottom deck. Channels 64 may be formed in one or both of the lower surface of the top deck and the top surface of the upper plate portion of the middle deck and in one or both of the bottom surface of the lower plate portion of the middle deck and the upper surface of the bottom deck. The reinforcement bars may be pultruded bars constructed of steel or fiberglass.

Numerous other modifications and adaptations of the present invention will be apparent to those skilled in the art and thus, it is intended by the following claims to cover all such modifications and adaptations which fall within the true spirit and scope of the invention. 

1. A plastic pallet comprising: a top deck having an upper surface and a lower surface; a middle deck having an upper plate portion and a lower plate portion spaced from each other and connected by a plurality of columns extending between a lower surface of said upper plate portion and a top surface of said lower plate portion, said upper plate portion having a top surface attached to said lower surface of said top deck; and a bottom deck having an upper surface and a lower surface, said upper surface of said bottom deck being attached to a bottom surface of said lower plate portion of said middle deck.
 2. The plastic pallet according to claim 1 wherein said middle deck is integrally molded as a single piece.
 3. The plastic pallet according to claim 2 wherein said top deck and said bottom deck are attached to said middle deck by a welding process.
 4. The plastic pallet according to claim 3 which further comprises at least one reinforcement member extending between one of said top deck and said bottom deck and said middle deck.
 5. The plastic pallet according to claim 4 wherein a channel for receiving said at least one reinforcing member is formed in one of said lower surface of said top deck and said top surface of said upper plate portion of said middle deck or in one of said bottom surface of said lower plate portion of said middle deck and said upper surface of said bottom deck.
 6. The plastic pallet according to claim 4 wherein a first reinforcement member extends between said top deck and said middle deck and a second reinforcement member extends between said bottom deck and said middle deck.
 7. The plastic pallet according to claim 6 wherein a plurality of first reinforcement members extend between said top deck and said middle deck and a plurality of second reinforcement members extend between said bottom deck and said middle deck.
 8. The plastic pallet according to claim 3 wherein said lower surface of said top deck has a plurality of first rib members thereon which mate with and are attached to a plurality of second rib members on said top surface of said upper plate portion of said middle deck.
 9. The plastic pallet according to claim 3 wherein said bottom surface of said lower plate portion of said middle deck has a plurality of third rib members thereon which mate with and are attached to a plurality of fourth rib members on said upper surface of said bottom deck.
 10. The plastic pallet according to claim 3 wherein said lower surface of said top deck has a plurality of first rib members thereon which mate with and are attached to a plurality of- second rib members on said top surface of said upper plate portion of said middle deck and wherein said bottom surface of said lower plate portion of said middle deck has a plurality of third rib members thereon which mate with and are attached to a plurality of fourth rib members on said upper surface of said bottom deck.
 11. The plastic pallet according to claim 3 wherein said welding process is a hot plate welding process.
 12. The plastic pallet according to claim 3 wherein said columns are aligned in rows between said upper and lower plate portions.
 13. The plastic pallet according to claim 3 wherein entryways for prongs of a lifting device are formed on at least one side of said pallet.
 14. The plastic pallet according to claim 13 wherein said entryways are formed on all four sides of said pallet. 